Implement esnprintf() and make formatted calls more efficient

Within the components, snprintf() was unchecked and had inefficient
calls in some places.
We implement esnprintf() that does all the dirty laundry for us
and use it exclusively now.

3 files changed, 49 insertions, 18 deletions

diff --git a/components/battery.c b/components/battery.c
index 90e8590..bcd42cd 100644
--- a/components/battery.c
+++ b/components/battery.c
@@ -14,9 +14,16 @@
 		int perc;
 		char path[PATH_MAX];
 
-		snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/",
-		         bat, "/capacity");
-		return (pscanf(path, "%d", &perc) == 1) ? bprintf("%d", perc) : NULL;
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/power_supply/%s/capacity",
+		              bat) < 0) {
+			return NULL;
+		}
+		if (pscanf(path, "%d", &perc) != 1) {
+			return NULL;
+		}
+
+		return bprintf("%d", perc);
 	}
 
 	const char *
@@ -32,8 +39,11 @@
 		size_t i;
 		char path[PATH_MAX], state[12];
 
-		snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/",
-		         bat, "/status");
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/power_supply/%s/status",
+		              bat) < 0) {
+			return NULL;
+		}
 		if (pscanf(path, "%12s", state) != 1) {
 			return NULL;
 		}
@@ -53,20 +63,29 @@
 		float timeleft;
 		char path[PATH_MAX], state[12];
 
-		snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/",
-		         bat, "/status");
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/power_supply/%s/status",
+		              bat) < 0) {
+			return NULL;
+		}
 		if (pscanf(path, "%12s", state) != 1) {
 			return NULL;
 		}
 
 		if (!strcmp(state, "Discharging")) {
-			snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/",
-					 bat, "/charge_now");
+			if (esnprintf(path, sizeof(path),
+                                      "/sys/class/power_supply/%s/charge_now",
+			              bat) < 0) {
+				return NULL;
+			}
 			if (pscanf(path, "%d", &charge_now) != 1) {
 				return NULL;
 			}
-			snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/",
-					 bat, "/current_now");
+			if (esnprintf(path, sizeof(path),
+			              "/sys/class/power_supply/%s/current_now",
+			              bat) < 0) {
+				return NULL;
+			}
 			if (pscanf(path, "%d", &current_now) != 1) {
 				return NULL;
 			}
diff --git a/components/netspeeds.c b/components/netspeeds.c
index b4e6972..6adc3ea 100644
--- a/components/netspeeds.c
+++ b/components/netspeeds.c
@@ -17,8 +17,11 @@
 
 		oldrxbytes = rxbytes;
 
-		snprintf(path, sizeof(path),
-		         "/sys/class/net/%s/statistics/rx_bytes", interface);
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/net/%s/statistics/rx_bytes",
+		              interface) < 0) {
+			return NULL;
+		}
 		if (pscanf(path, "%llu", &rxbytes) != 1) {
 			return NULL;
 		}
@@ -37,8 +40,11 @@
 
 		oldtxbytes = txbytes;
 
-		snprintf(path, sizeof(path),
-		         "/sys/class/net/%s/statistics/tx_bytes", interface);
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/net/%s/statistics/tx_bytes",
+		              interface) < 0) {
+			return NULL;
+		}
 		if (pscanf(path, "%llu", &txbytes) != 1) {
 			return NULL;
 		}
diff --git a/components/wifi.c b/components/wifi.c
index 591f6ad..b3e1723 100644
--- a/components/wifi.c
+++ b/components/wifi.c
@@ -23,8 +23,11 @@
 		char status[5];
 		FILE *fp;
 
-		snprintf(path, sizeof(path), "%s%s%s", "/sys/class/net/", iface,
-		         "/operstate");
+		if (esnprintf(path, sizeof(path),
+		              "/sys/class/net/%s/operstate",
+		              iface) < 0) {
+			return NULL;
+		}
 		if (!(fp = fopen(path, "r"))) {
 			warn("fopen '%s':", path);
 			return NULL;
@@ -69,7 +72,10 @@
 
 		memset(&wreq, 0, sizeof(struct iwreq));
 		wreq.u.essid.length = IW_ESSID_MAX_SIZE+1;
-		snprintf(wreq.ifr_name, sizeof(wreq.ifr_name), "%s", iface);
+		if (esnprintf(wreq.ifr_name, sizeof(wreq.ifr_name),
+		              "%s", iface) < 0) {
+			return NULL;
+		}
 
 		if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 			warn("socket 'AF_INET':");